Curiosity is carrying the most advanced payload of scientific gear ever used on Mars' surface, a payload more than 10 times as massive as those of earlier Mars rovers. Its assignment: investigate whether conditions have been favorable for microbial life and for preserving clues in the rocks about possible past life. Here, an engineering model of the Curiosity rover is tested in the Dumont Dunes near Baker, Calif., on May 10, 2012.

NASA’s Mars Science Laboratory mission set down a large mobile laboratory, the rover Curiosity, using precision-landing technology that makes many of Mars’ most intriguing regions viable destinations for the first time. During the 23 months after landing, Curiosity will analyze dozens of samples drilled from rocks or scooped from the ground as it explores with greater range than any previous Mars rover.